A sad artifact of search engines having become the navigation paradigm for the web, is that gaming the system came into vogue. Carpetbaggers in the form of SEO "experts" started manipulating content to get better search engine rankings, and selling their wares to unsuspecting websites wanting "better results page placement."
Note that SEM is radically different from SEO, and I consider SEM a legitimate industry.
Guess what? 99.9999.....% of what these SEO "experts" do can be easily done by anyone, and unfortunately, the "experts" have built up such a layer of falsification and search algorithm manipulation that legitimate content has to fight tooth and nail to be properly represented. If you're interested in all the relevant tips/tricks on SEO, all you need to do is buy the seobook; it'll tell you everything you need to know, and it's updated regularly in order to keep close pace with algorithm changes. We'll leave it to Google/Yahoo/MSFT to sort through the math in order to keep the "right" stuff at the top of the page, but the rest of us simply need to focus on what matters; your product and content. If you deserve first-page placement, you will get it; you can't buy it. The few examples I've experienced in my life wherein someone manipulated the model to get first-page placement, the algorithms caught up to them, snuffed them out, and their SEO investment was lost. If you're reading this thinking "but, I've been on the front page b/c of SEO for months now", your days are numbered; figure out a different model quickly.
The upside here is that the marketplace is evolving. Just like any opportunity that is taken advantage of, and over used, it becomes commoditized. SEO is no different. Some friends of mine have recognized this and are building a service that cuts out the noise, and allows folks that want their site to be SEO'd, to have it done by people that know what they're doing (self-regulated marketplace style), at costs that are in-line with the reality of the market; as opposed to glorified SEO gurus. You'll hear about this firm soon enough; I'm excited to see them set things straight.
There is incredible money to be made by a site owner, as well as by people that know how to SEO, if you get "good" placement on a search result page. The industry needs a reset on the model here however, and I'm looking forward to it.